A positive photosensitive composition comprises: (A) a resin that has an acid decomposable repeating unit represented by formula (I) and increases its solubility in an alkali developer by action of an acid: (B) a compound generating an acid upon irradiation with actinic light or radiation; (C) a hydrophobic resin insoluble in an alkali developer and having at least either one of a fluorine atom and a silicon atom; and (D) a solvent, ##STR00001## wherein in the formula (I), Xa.sub.1 represents a hydrogen atom, an alkyl group, a cyano group or a halogen atom, Ry.sub.1 to Ry.sub.3 each independently represents an alkyl group or a cycloalkyl group, and at least two of Ry.sub.1 to Ry.sub.3 may be coupled to form a ring structure, and Z represents a divalent linking group.